Here we investigated the affect of 150 visitors before and after the following three types of interaction with dolphins: observing dolphins, touching dolphins for 1 min under the guidance of an instructor, and swimming with two dolphins and one instructor for 10 min. Negative affects, positive engagement (high arousal and positive affect), and tranquility (low arousal and positive affect) before and after each interaction were measured. Negative affect and tranquility levels significantly decreased and increased, respectively, independent of the type of interaction. On the other hand, positive engagement levels increased after all types of interaction; however, the magnitude of this increase was significantly greater in visitors who touched the dolphins than in those who merely observed them. These variations in positive engagement across different interactions enhanced our understanding of the effects of different interactions with dolphins on people’s affects.